It's not really clear to me what you're asking. The function read is a method of the typeclass Read, and it has type Read a => String -> a. There are a number of instances of the typeclass Read in the standard prelude (http://www.haskell.org/onlinereport/standard-prelude.html) Notably, instance Read Int where ... instance (Read a, Read b) => Read (a,b) where ... instance (Read a) => Read [a] where ... which, taken together, imply that the type [(Int,Int)] is in the typeclass Read, and so there is a suitable implementation of read :: String -> [(Int,Int)] If you want to see how that might be implemented (though haskell implementations are allowed to do the same thing in a different way), see the link to the prelude there. hope this helps, - Cale On 4/21/05, Walt Potter wrote:

I'd like to find a reference to reading with patterns such as read::[(Int,Int)]

Thanks, Walt